A tropical wave in the western Caribbean approaching Mexico's Yucatan Peninsula is generating disorganized thunderstorms. Wind shear is a moderate 10 - 15 knots over the region, and water vapor satellite images show that there is some dry air to the west that will interfere with any development that might occur. None of the reliable computer models develop this wave, and NHC is giving it a 10% chance of developing into a tropical depression.

Figure 1. Morning satellite image of the disturbed region of weather of the coast of Africa, south of the Cape Verdes Islands.

The GFS, NOGAPS, and ECMWF models continue to predict that a tropical storm will form between Africa and the Lesser Antilles Islands sometime in the period 3 - 6 days from now. There is an area of disturbed weather south of the Cape Verdes Islands, but there is no obvious organization to the cloud pattern. Wind shear is a hefty 20 - 30 knots in the region, and the disturbance is a 1 - 2 day journey away from reaching a lower shear area where development can occur. Preliminary indications are that if a storm did develop in this region, it would track west-northwest and pass well to the northeast of the Lesser Antilles Islands 7 - 8 days from now. However, 7-day forecasts of a storm that hasn't even formed yet are not to be trusted.

Figure 2. The cold front that brought an end to the Great Russian Heat Wave of 2010 lies east of Moscow in the NASA MODIS photo taken at 8:35 UTC August 19, 2010. Smoke from wildfires is visible over a wide swath of Russia east of the front. Image credit: NASA.

The Great Russian Heat Wave of 2010 endsA powerful cold front swept through Russia yesterday and today, finally bringing an end to the Great Russian Heat Wave of 2010. Temperatures at Moscow's Domodedovo airport hit 25°C (77°F) today, which is still 4°C (7°F) above average, but the high temperature since late June. Moscow has seen 62 consecutive days with a high temperature above average, but the latest forecast for Moscow predicts that remarkable string will come to an end Friday, when the high will reach just 17°C (62°F).

Massive 926 mb extratropical storm generating huge waves off AntarcticaOne of the most intense extratropical storms in recent years is churning up the waters near the coast of Antarctica in the South Indian Ocean. The powerful storm peaked in intensity yesterday afternoon with a central pressure of 926 mb--the type of pressure typically found in a Category 4 hurricane. Storms this intense form on average once per year, or perhaps less often, according to an email I received from Jeff Callaghan of the Australia Bureau of Meteorology. Since extratropical storms do not form eyewalls, the winds at the surface from this monster storm probably reached "only" 100 - 120 mph (equivalent to a Category 2 or 3 hurricane.) The storm is forecast to generate huge waves with a significant wave height of 13 meters (44 feet) today, according to the NOAA Wavewatch III model (Figure 3.) I have flown into an extratropical storm this intense--in 1989, I participated in a field project based in Maine that intercepted a remarkable extratropical storm that "bombed" into a 928 mb low south of the Canadian Maritime provinces. You can read my story of that somewhat harrowing flight here.

Figure 3. Satellite image taken at 8:10 UTC August 19, 2010, showing the intense extratropical cyclone that has weakened to 940 mb in the South Indian Ocean near the coast of Antarctica. Image credit: NASA.

Figure 4. Surface pressure analysis from 18 UTC August 18, 2010, showing a 926 mb low in the South Indian Ocean, just north of Antarctica. Image credit: Jeff Callaghan, Australia Bureau of Meteorology.

Figure 5. Predicted wave height from the NOAA Wavewatch III model for 2pm EDT (18 UTC) today, August 19, 2010. Peak wave heights of 13 meters (44 feet) are projected over ocean areas between Antarctica and Australia. Long-period waves (19 seconds between crests) up to 7 meters (22 feet) high are predicted to affect the southwest coast of Australia by Sunday. The waves are predicted to propagate eastwards to New Zealand 8 - 9 days from now, and be a respectable 4 - 5 meters high then.

Quoting MiamiHurricanes09:A profession meteorologist said this on Storm2k and I quote:

"Given the current and projected -NAO, CV storms are less likely to be a U.S. threat. It's the closer-in development in the Caribbean and SW Atlantic that would be the threat to the U.S. Anything forming by the CV islands will have a hard time making it west to the U.S."

Quoting MiamiHurricanes09:A profession meteorologist said this on Storm2k and I quote:

"Given the current and projected -NAO, CV storms are less likely to be a U.S. threat. It's the closer-in development in the Caribbean and SW Atlantic that would be the threat to the U.S. Anything forming by the CV islands will have a hard time making it west to the U.S."

I find this to be incorrect...any opinions anyone?

A negative NAO is the exact opposite, amazes me that someone who is a professional would say that

"Given the current and projected -NAO, CV storms are less likely to be a U.S. threat. It's the closer-in development in the Caribbean and SW Atlantic that would be the threat to the U.S. Anything forming by the CV islands will have a hard time making it west to the U.S."

SURFACE...A SURFACE TROUGH IS OVER THE GULF OF CALIFORNIA FROM 32N114W TO 23N108W. SCATTERED MODERATE TO STRONG CONVECTION IS OVER THE SOUTHERN PORTION OF THE TROUGH FROM 21N TO 27N BETWEEN 107W AND 111W. ANOTHER SURFACE TROUGH IS ALONG THE COAST OF SOUTHERN MEXICO FROM 19N107W TO 15N100W TO 12N92W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 14N TO 20N BETWEEN 102W AND 108W...AND FROM 10N TO 15N BETWEEN 93W AND 97W. GFS MODEL GUIDANCE SHOWS LITTLE CHANGE IN THE PRIMARY SURFACE FEATURES AND ITS ASSOCIATED CONDITIONS OVER THE NEXT DAY OR SO.

I do know the formation potential chart from earlier today was hyping that area...

Quoting StormW:If we remain in a negative NAO, this is the most likely pattern:

Here is the excerpt again from the article I posted earlier. Does it kinda match the picture?

Ridging over the eastern and western sides of the North Atlantic basin during the hurricane season displaces the middle tropospheric trough of lower pressures to the north. The trough, which induces hurricane movement to the north and east, is therefore unable to recurve hurricanes that are moving westward toward the United States thus increasing the probability of landfalls along the Gulf and southeast coasts.

Is the ridging the green, yellow and red part that runs across the top? I mean it may be a stupid question, but I just don't care. I am used to being chuckled at....

Why should the models be any more accurate 5 to 6 days out about where a trough is going to be as anything else. I do think they are initializing this system coming of Africa now with the one of two days ago. Even that said look a the northern most system it has been trending wsw in my opinion. Looking at current visible I can see where they would forecast exactly the path they have. I believe most on here think the high is building west in the Atlantic. Will be fun to watch.

Quoting washingtonian115: There's a saying in the met world that just by looking at a storms name you can tell if their going to be something or not.If indications verifie It looks like Igor will form in september which is the most favorable month for hurricanes.just saying..

Hmmmm...

Alex does sound a little mean.Bonnie sounds weak.Colon just sounds like a weak storm with a curved band...oh, no....never mind...that's...that's pretty gross. LOL.

Quoting sailingallover:I have crossed large sections of oceans using the models as guidance. I have seen way more times they were very accurate up to 120hrs and good guidance to 180hrs than times they were very wrong. As far as hurricanes and storms this season EMCWF and GFS have done a pretty good job. I'm not saying this might not make land, the low may never develop off the coast. But right now they all pretty much agree and the basis for everything from the storm forming to the trough over the middle CONUS are there.

Well, u have experience I don't; I've only used them for this kind of thing: tropical wx forecasting. My instinct with anything after 3 days is that it's possible, but not automatically probable. However, I have to agree that the models have been improving, bit by bit, in the longer range forecasts.

There's a saying in the met world that just by looking at a storms name you can tell if their going to be something or not.If indications verifie It looks like Igor will form in september which is the most favorable month for hurricanes.just saying..

Whoa, the 18z GFS really did go aggressive on its solution for PGI31L. The closest isobar to the center reads '984'mb that would likely translate to 970mb in the central pressure and then to around 940-930mbmb in real life. Where the area of low pressure is appears to me cloud-less...interesting...an eye on the GFS?

Quoting BahaHurican: Somebody said it in here before; trust the models - if u trust them - 72 hours out MAX. After that it's all fictions and fairy tales. 72 hrs out, we're pretty likely to see storm formation of some kind. After that? it's anybody's guess.....

I have crossed large sections of oceans using the models as guidance. I have seen way more times they were very accurate up to 120hrs and good guidance to 180hrs than times they were very wrong. As far as hurricanes and storms this season EMCWF and GFS have done a pretty good job. I'm not saying this might not make land, the low may never develop off the coast. But right now they all pretty much agree and the basis for everything from the storm forming to the trough over the middle CONUS are there.